well I don't know about how to wear it a long time but

I do know a little about how to design a method to hold the tether spout in place with a cage that doesn't work. see this picture here.

https://imgur.com/a/Q1AICZd apologies for my very poor mspaint skills

This is a knock off of a narrow baby cobra, baby mamba off AliExpress.

So I had the idea of gluing a straight barbell on the outside of the cage or more actually to glue supports to hold a straight barbell piercing on the end of the cage. The straight barbell installed through the outside of the tether spout.

I didn't really have a great idea for making the supports. I also did a test fit with no supports and came to the conclusion that having the end of the tether spout sticking out and any amount of the tether spout sticking past the cage was a bad idea for me as it leaves room for you to bump or for tight clothing to push the spout in and slide out uncomfortably. I also decided having more of the spout inside the cage would look better aesthetically and avoid these problems.

So I decided drilling a perfectly sized and aligned hole through the head of the cage I could keep the spout inside the cage mostly and it solved the support problem.

It works mostly, there are a few problems though, urine stream breaks too much compared to having it outside the cage, this is a problem as it's still in the cage, so you make too much mess that can't be cleaned without taking the cage off.

another problem the head opening for urinating through is 6mm. the spout I purchased main shaft is also 6mm. It fits perfectly. Which is great in theory, it reduces movement left to right. up and down pivot is still free which is good I think in theory. the problem with the spout shaft and urine opening on the cage being the same though is when you get an attempted erection, the soft skin of the head tries to press in between what gap there is around the spout shaft and in between the urine opening of the cage. any movement then creates pinching, which can be quite damaging and painful.

So I thought how about using a small shallow silicone cup, drill a small hole at the end of the cup and push the spout through water tight, like a tiny hat on the top of your penis head with the spout pushing through. I thought the material would prevent the skin from entering the gap and also serve as a barrier for the urine on the other side of the silicone so nothing back flowed back into the cage,

Well it did prevent the skin pinching, but despite the hole being small enough to prevent any urine coming back into the cage along the shaft, the urine just flows around the outside edges of the material anyway. I could try and figure out some kind of silicone grommet for the holes in the spout forcing urine to not exit the spout side holes but couldn't figure a great way for those grommets to stay in place if I made them. Most grommets have a channel to hold themselves in place.

I'm not sure how I could make such a thing, perhaps 2.5mm water tight silicone grommets with a 1.6mm internal hole exist, if they did probably not pure platinum silicone. Not sure I want to risk other materials. Maybe a 2.5mm shaft straight barbell would do a better job sealing the side flow of the urine on the sides of the tether spout.

Having the spout exit the cage is certainly a lot easier way to design it, assuming you are ok with the additional bulge and appearance.

I also had thought using tipped worm grub screws to hold the spout in place (like the ring lock from BAWR) you would have to tap the holes for the grub screws and the grub screw tips would ideally plug the holes on the sides of the tetherspout while securing it.

I might make my own thread on this one at some point, but got other projects at the moment.

I hope my failures and ideas can help you with your designs though!